Refine Your Search

Search Results

Viewing 1 to 6 of 6
Journal Article

Method of Vehicle Dynamics Analysis by Means of Equivalent Cornering Stiffness for Aerodynamic Forces and Moments

2012-04-16
2012-01-0213
The dynamic performance of a vehicle traveling at high speeds is affected by the aerodynamic characteristics consisting of lift on front and rear axles, side force, and yawing moment. In order to enable consideration of these aerodynamic characteristics from the early stages of the vehicle development process, it is required that the characteristics are replaced by simple development indices. The study discussed in this paper introduced the concept of equivalent cornering stiffness to analyze these aerodynamic characteristics from the viewpoint of vehicle dynamics. Using this method, it is possible to integrate four aerodynamic characteristics into two variables which are very important to vehicle dynamics. As a result, the interaction between each aerodynamic characteristic is simply expressed in the equations of motion. Moreover the aerodynamic characteristics are dealt with as the same variables which are commonly used in other chassis systems such as suspensions and tires.
Journal Article

Quantitative Representations of Aerodynamic Effects on Handling Response and Flat Ride of Vehicles

2012-04-16
2012-01-0445
The effects of aerodynamic coefficients on handling response and flat ride were quantified. For handling response, the aerodynamic effect was quantified by analysis with linear representation and a two-wheel simulation model, using aerodynamic coefficients obtained from a full scale car wind tunnel. The correlation of aerodynamic coefficients and handling response with driving feel was also ascertained. Aerodynamic yaw moment and side-force were also converted to equivalent front and rear lift to standardize aerodynamic indexes and improve aerodynamic development efficiency. For flat ride, steady and unsteady aerodynamic effects were quantified by analysis with a two-degree-of-freedom mass-spring-damper simulation model and aerodynamic coefficients obtained from a 35% scale model wind tunnel and towing tank test. Unsteady aerodynamic force occurrence mechanism was ascertained by unsteady CFD using dynamic mesh.
Technical Paper

Effect of Unsteady Lift Force on Vehicle Dynamics in Heave and Pitch Motion

2014-04-01
2014-01-0576
The change in the aerodynamic lift force (henceforth CL) by heave motion is discussed in this paper in order to clarify the effect of aerodynamic characteristics on the vehicle dynamic performance. We considered that phenomenon in actual car running at 160km/h and 1Hz heave frequency. Using a towing tank to change its water from the air to the working fluid to more easily observe this phenomenon. That makes possible to observe the same phenomenon with reduced velocity and small models under same Strouhal number condition. This method can be reducing vehicle speed to 3m/s (1/15 actual) and frequency to 0.2Hz (1/5 actual) in case using 40% scaled model. The results of these tests showed that unsteady CL is proportional to heave motion. These results showed the proportional relationship between unsteady CL and heave motion. The formularization of unsteady CL made it possible to introduce shape coefficients to vehicle dynamics simulations as functions of heave velocity.
Technical Paper

Elastokinematic Characteristics of Torsion Beam Suspensions

2015-04-14
2015-01-1497
Torsion beam suspensions are lightweight and low in cost, and they are therefore frequently used as the rear suspensions of small front-wheel drive vehicles. However, it is difficult to predict their characteristics and to satisfy performance targets in the early stages of development in particular, because the various aspects of performance required of a suspension must be achieved by a single structure. A great deal of research has been conducted into the cross-sectional shape of the beam section; however, this paper focuses on the effect of the properties of the trailing arms on suspension characteristics. Two similar test torsion beam suspensions differing only in the rigidity of the trailing arms were fabricated, and kinematics and compliance (K&C) tests were conducted using a 3D measurement system. The lateral compliance test showed the anticipated result that change in toe and camber is greater in the suspension with lower rigidity trailing arms.
Journal Article

Prediction Method for Water Intrusion into the Engine Air Intake Duct while Running on Flooded Road at the Early Stage of Vehicle Development

2017-03-28
2017-01-1322
Vehicles are required durability in various environments all over the world. Especially water resistance on flooded roads is one of the important issues. To solve this kind of problem, a CFD technology was established in order to predict the water resistance performance of the vehicle at the early development stage. By comparison with vehicle tests on flooded roads, it is clarified the following key factors are required for accurate prediction; the vehicle velocity change, the vehicle height change and the air intake flow rate. Moreover, these three key factors should be appropriately determined from vehicle and engine specification to predict water intrusion for flooded roads at the early stage of development. In this paper, a methodology which determines appropriate analysis conditions mentioned above for flooding simulation from vehicle and engine specification is described. The methodology enables us to determine whether the vehicle provides sufficient waterproofness.
Technical Paper

Aerodynamic Development of the New Honda FIT/JAZZ

2015-04-14
2015-01-1535
This paper discusses the characteristic flow field of the new Honda FIT/Jazz as determined from the aerodynamic development process, and introduces the technique that reduced aerodynamic drag in a full model change. The new FIT was the first model to take full advantage of the Flow Analysis Simulation tool (FAST), our in-house CFD system, in its development. The FAST system performs aerodynamic simulation by automatically linking the exterior surface design with a predefined platform layout. This allows engineers to run calculations efficiently, and the results can be shared among vehicle stylists and aerodynamicists. Optimization of the exterior design gives the new FIT a moderate pressure peak at the front bumper corner as compared to the previous model, resulting in a smaller pressure difference between the side and underbody.
X